Hakan wrote:

This is a wired question but the participants here are so knowledgeable
I am sure this is old hat... On a business trip I encountered a network where I was unable to log on
using my ThinkPad and the wired NIC.  The network supposedly used DHCP
but my system was unable to obtain an IP address despite multiple
attempts, even after rebooting (also on different days).  I eventually
was able to log on using a static IP address but also had supply the
DNS addresses as I was otherwise unable to surf the 'net.  I should add
that this was an office network with many users and others temporarily
using it like myself had no problems with their Win systems.

What might the problem have been?  TIA.

This sounds similar (though it may not actually be related) to an issue that I have recently ran into that previously I would have said would not be an issue.  I have a customer that has recently gone from using static ip's nationwide to almost all of them using dhcp with regional dhcp servers.  During the transition the users were switched via a Tivoli push.  Some of these user were suddenly getting "cable disconnect".  I ended up having to change, of all things, the dns suffix search order.  I don't recall now even how I stumbled on that as being the issue but afterwards found that those that had that problem (and happened to have admin rights) I could change the dns suffix search order and get them connected.  What is really odd is that it is not universal... some people connect just fine without anything set in there.  To test this though, I would after getting them connected remove the dns suffix search order and it would go back to "Cable disconnect", they then got connected again when adding it back in.
Andy